There is a rack mount device for housing an electronic device such as a server in a rack. This type of rack mount device is disclosed in, for example, Japanese Laid-open Patent Publication No. 2001-244663 and Japanese Laid-open Patent Publication No. 2012-94708. This type of rack mount device includes, for example, a rail which is provided in a rack and guides an electronic device into the rack and a claw-shaped hooking portion which is provided at an end portion of the rail and is hooked to a rear lower surface of the electronic device. When the electronic device is drawn out from the rack, the hooking portion is hooked to the rear lower surface of the electronic device, so that the electronic device is stopped from dropping off from the rail.